共查询到20条相似文献,搜索用时 15 毫秒
1.
Swati Mukhopadhyay Iswar Chandra Mondal Rama Subba Reddy Gorla 《Heat and Mass Transfer》2012,48(6):915-921
The aim of this paper is to present the boundary layer flow of viscous incompressible fluid due to a porous vertical stretching surface with a power-law stretching velocity in a thermally stratified medium. Using a special form of Lie group transformations viz. scaling group of transformations, similarity solutions for this problem are obtained. The equations are then solved numerically. With increasing values of the stratification parameter, the velocity as well as temperature decreases. At a particular point of the porous stretching sheet, the velocity decreases with the increasing suction parameter. The dimensionless temperature at a point of the sheet decreases due to suction but increases due to injection. The findings of this study reveal that stratification and suction can be used as means of cooling the boundary layer flow region. 相似文献
2.
Mahantesh M. Nandeppanavar K. Vajravelu M. Subhas Abel M. N. Siddalingappa 《Meccanica》2013,48(6):1451-1464
In this paper we analyze the flow and heat transfer of an MHD fluid over an impermeable stretching surface with variable thermal conductivity and non-uniform heat source/sink in the presence of partial slip. The governing partial differential equations of the problem are reduced to nonlinear ordinary differential equations by using a similarity transformation. The temperature boundary conditions are assumed to be linear functions of the distance from the origin. Analytical solutions of the energy equations for Prescribed Surface Temperature (PST) and Prescribed Heat Flux (PHF) cases are obtained in terms of a hypergeometric function, without applying the boundary-layer approximation. The effects of the governing parameters on the flow and heat transfer fields are presented through tables and graphs, and they are discussed. Furthermore, the obtained numerical results for the skin friction, wall-temperature gradient and wall temperature are analyzed and compared with the available results in the literature for special cases. 相似文献
3.
In this paper, viscous flow and heat transfer over an unsteady stretching surface is investigated with slip conditions. A
system of non-linear partial differential equations is derived and transformed to ordinary differential equations with help
of similarity transformations. Numerical computations are carried out for different values of the parameters involved and
the analysis of the results obtained shows that the flow field is influenced appreciably by the unsteadiness, and the velocity
slip parameter. With increasing values of the unsteadiness parameter, fluid velocity and the temperature are found to decrease
in both the presence and absence of slip at the boundary. Fluid velocity decreases due to increasing values of the velocity
slip parameter resulting in an increase in the temperature field. Skin-friction decreases with the velocity slip parameter
whereas it increases with unsteadiness parameter. The rate of heat transfer decreases with the velocity slip parameter while
increases with unsteadiness parameter. Same feature is also noticed for thermal slip parameter. 相似文献
4.
Jong Sun Park Seung Mo Kim Min Soo Kim 《International Journal of Computational Fluid Dynamics》2013,27(3):263-276
A numerical study was performed on flow and heat transfer involving moving free surfaces that occurs in mold filling processes such as casting and injection molding. In these problems, the calculation domain changes continuously and the numerical treatment of the moving interface tends to cause artificial diffusion. Among the solution algorithms based on the Eulerian method, the volume-of-fluid (VOF) method was used because the method is simple and efficient in handling the complex flow patterns inside the cavity. To solve the transport equation of free surface without artificial smearing of the interface the baby-cell method was employed in the geometric reconstruction of the free surface. Furthermore, a predictor–corrector method was adopted in the time integration of volume-of-fluid (VOF) transport equation to increase the accuracy. The proposed scheme was verified through several benchmark problems. In order to show the capability of the proposed method, several three-dimensional mold filling processes were solved. The current algorithm was applied to the floating body problem. Three-dimensional floating body problems were tested. 相似文献
5.
A fractal model for the subcooled flow boiling heat transfer is proposed in this paper. The analytical expressions for the subcooled flow boiling heat transfer are derived based on the fractal distribution of nucleation sites on boiling surfaces. The proposed fractal model for the subcooled flow boiling heat transfer is found to be a function of wall superheat, liquid subcooling, bulk velocity of fluid (or Reynolds number), fractal dimension, the minimum and maximum active cavity size, the contact angle and physical properties of fluid. No additional/new empirical constant is introduced, and the proposed model contains less empirical constants than the conventional models. The proposed model takes into account all the possible mechanisms for subcooled flow boiling heat transfer. The model predictions are compared with the existing experimental data, and fair agreement between the model predictions and experimental data is found for different bulk flow rates. 相似文献
7.
8.
Applied Mathematics and Mechanics - The heat transfer rate of the thermal Marangoni convective flow of a hybrid nanomaterial is optimized by using the response surface methodology (RSM). The... 相似文献
9.
The solution to the unsteady mixed convection boundary layer flow and heat transfer problem due to a stretching vertical surface
is presented in this paper. The unsteadiness in the flow and temperature fields is caused by the time-dependent of the stretching
velocity and the surface temperature. The governing partial differential equations with three independent variables are first
transformed into ordinary differential equations, before they are solved numerically by a finite-difference scheme. The effects
of the unsteadiness parameter, buoyancy parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly
examined. Both assisting and opposing buoyant flows are considered. It is observed that for assisting flow, the solutions
exist for all values of buoyancy parameter, whereas for opposing flow, they exist only if the magnitude of the buoyancy parameter
is small. Comparison with known results for steady-state flow is excellent. 相似文献
10.
《应用数学和力学(英文版)》2019,(7)
This study investigates the cilia transport phenomenon from the perspectives of the heat transfer and variable viscosity in a bending channel. The rightward wall is maintained at a temperature of T_0, and the leftward wall has a temperature of T_1. Each wall has a metachronal wave that travels along its wall. The structures of the ciliary assemblies are calculated by the well-known simplifying suppositions of the large wavelength and the small Reynolds number approximation. The flow phenomenon for the Newtonian fluid is described as a function of cilia and a metachronal wave velocity. The pressure rise is calculated with MATHEMATICA. The theme of the cilia beating flow is inspected with scheming plots, and its features are discussed at the end of the article. 相似文献
11.
Flow and heat transfer over a permeable sensor surface placed in a squeezing channel is analyzed. A constant transpiration
through the sensor surface is assumed. Locally non-similar momentum and energy equations are solved by three different methods,
against the transpiration parameter τ, for different values of the squeezing parameter b, and Prandtl number Pr. From the investigation, it is found that when the channel being squeezed, the skin-friction reduces but the heat transfer
coefficient increases. Increase in the value of the squeezing parameter onsets reverse flow at the sensor surface when fluid
is being injected and the affect is enhanced with the increase of injection through the surface. It is further observed that
increase of suction of fluid through the sensor thins the thermal and the momentum boundary layer regions, whereas injection
of fluid leads to thickening of both the thermal and the momentum boundary layer regions. Heat transfer from the surface of
the sensor increases with the increase of the value of Pr for the entire range of surface mass-flux parameter τ.
M. A. Hossain is on leave of absence from University of Dhaka. 相似文献
12.
Emad M. Abo-Eldahab 《Heat and Mass Transfer》2005,41(8):734-743
A general analysis has been developed to study the combined effect of the free convective heat and mass transfer on the steady three-dimensional laminar boundary layer flow over a stretching surface. The flow is subject to a transverse magnetic field normal to the plate. The governing three-dimensional partial differential equations for the present case are transformed into ordinary differential equation using three-dimensional similarity variables. The resulting equations, are solved numerically by applying a fifth order Runge-Kutta-Fehlberg scheme with the shooting technique. The effects of the Magnetic field Parameter M, buoyancy parameter N, Prandtl number Pr and Schmidt number Sc are examined on the velocity, temperature and concentration distributions. Numerical data for the skin-friction coefficients, Nusselt and Sherwood numbers have been tabulated for various parametric conditions. The results are compared with known from the literature. 相似文献
13.
An analysis is carried out to study the momentum, mass and heat transfer characteristics on the flow of visco-elastic fluid (Walter's liquid-B model) past a stretching sheet in the presence of a transverse magnetic field.In heat transfer, two cases are considered:
- 1.
- The sheet with prescribed surface temperature (PST case); and
- 2.
- The sheet with prescribed wall heat flux (PHF case).
14.
15.
An analysis is made of steady two-dimensional oblique stagnation-point flow and radiative heat transfer of an incompressible viscous fluid towards a shrinking sheet which is shrunk in its own plane with a velocity proportional to the distance from a fixed point. Here the axis of the stagnation flow and that of the shrinking sheet are not aligned. A similarity transformation reduces the Navier-Stokes equations to a set of non-linear ordinary differential equations and are solved numerically using a shooting technique. The analysis of the results obtained shows that multiple solutions exist for a certain range of the ratio of the shrinking velocity to the free stream velocity. The effect of non-alignment for the wall shear stress and the horizontal velocity components are discussed. Streamline patterns are also shown for shrinking at the sheet with aligned and non-aligned cases. It is found that the temperature at a point in the fluid decreases with increase in effective Prandtl number (Pr eff ). The results pertaining to the present study indicate that as Pr eff increases, the rate of heat transfer also increases. The reported results are in good agreement with the available published work in the literature. 相似文献
16.
The steady laminar boundary layer flow and heat transfer from a warm, laminar liquid flow to a melting surface moving parallel
to a constant free stream is studied in this paper. The continuity, momentum and energy equations, which are coupled nonlinear
partial differential equations are reduced to a set of two nonlinear ordinary differential equations, before being solved
numerically using the Runge–Kutta–Fehlberg method. Results for the skin friction coefficient, local Nusselt number, velocity
profiles as well as temperature profiles are presented for different values of the governing parameters. Effects of the melting
parameter, moving parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. It is
found that the problem admits dual solutions. 相似文献
17.
Arthur E. Bergles 《Heat and Mass Transfer》2011,47(8):1001-1008
Enhanced heat transfer has evolved into an important component of heat transfer experimentation and theory. The accumulated
literature includes thousands of references. To give an overview of the current state of this important technology—for the
past ten years, representative developments in each category of enhancement techniques are cited and commented on. The discussion
is divided into the literature, passive enhancement techniques, active enhancement techniques, and compound enhancement techniques. 相似文献
18.
Exact solutions for an incompressible, viscoelastic, electrically conducting MHD aligned fluid are obtained for velocity components and temperature profiles. Lie Group method is applied to obtain the solution and the symmetries used are of translational type.The English text was polished by Keren Wang and Yunming Chen. 相似文献
19.
The present paper focuses on the analysis of unsteady flow and heat transfer regarding an axisymmetric impinging synthetic
jet on a constant heat flux disc. Synthetic jet is a zero net mass flux jet that provides an unsteady flow without any external
source of fluid. Present results are validated against the available experimental data showing that the SST/k − ω turbulence model is more accurate and reliable than the standard and low-Re k − ε models for predicting heat transfer from an impinging synthetic jet. It is found that the time-averaged Nusselt number
enhances as the nozzle-to-plate distance is increased. As the oscillation frequency in the range of 16–400 Hz is increased,
the heat transfer is enhanced. It is shown that the instantaneous Nu distribution along the wall is influenced mainly by the interaction of produced vortex ring and wall boundary layer. Also,
the fluctuation level of Nu decreases as the frequency is raised. 相似文献
20.
The similarity solution for the problem of mixed convection boundary layer flow adjacent to a stretching vertical sheet in an incompressible electrically conducting fluid in the presence of a transverse magnetic field is presented. It is assumed that the sheet is stretched with a power-law velocity and is subjected to a variable surface heat flux. The governing partial differential equations are first transformed into a system of non-linear ordinary differential equations, before being solved numerically by the Keller-box method. The numerical results obtained are then compared with previously reported cases available in the literature as well as the series solution for certain values of parameters, to support their validity. The effects of the governing parameters on the flow field and heat transfer characteristics are obtained and discussed. 相似文献